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Astronomers spot embryo star growing in stellar 'womb'

Rare find: Some of the antennas that form the ALMA project, which discovered the star embryo. Photo: Reuters

Astronomers have reported their best observation yet of a massive star embryo growing within a dark cloud - the largest stellar ''womb'' ever spotted in our Milky Way.

The star, which could grow to 100 times the mass of the sun and up to a million times brighter, was spotted by the most powerful radio telescope on Earth - the ALMA international astronomy facility in Chile, according to a paper published in the journal Astronomy & Astrophysics.

Finding such a massive object so early in its evolution in our galaxy is a spectacular result.

Astronomers hope its discovery, at a distance of 11,000 light years from Earth, will shed light on how these exceptionally massive stars are formed, shrouded as they are in dust and mystery.

''Not only are these stars rare, but their births are extremely rapid and childhood short, so finding such a massive object so early in its evolution in our galaxy is a spectacular result,'' study co-author Gary Fuller of the University of Manchester said in a statement issued by the European Southern Observatory.

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The most massive and brightest stars in the galaxy form within cool and dark cloud cores, hungrily feeding on material being dragged inwards by the embryo star's gravitational pull.

This specific star is located in the Spitzer Dark Cloud, whose core has a mass about 500 times that of the sun.

''This object is expected to form a star that is up to 100 times more massive than the sun. Only about one in 10,000 of all stars in the Milky Way reach that kind of mass,'' said study lead author Nicolas Peretto of Cardiff University.

''The remarkable observations from ALMA allowed us to get the first really in-depth look at what was going on within this cloud. We wanted to see how monster stars form and grow, and we certainly achieved our aim. One of the sources we have found is an absolute giant - the largest protostellar core ever spotted in the Milky Way.''

According to the observatory, there are two theories on the formation of massive stars, which have at least 10 times the mass of the sun. The first theory suggests that parental dark clouds fragment, creating several small cores that collapse and form stars. The other sees the entire cloud collapse inwards, with material racing into its centre to feed the star or stars growing there.

The new results support the second theory, said the statement.

''The ALMA observations reveal the spectacular details of the motions of the filamentary network of dust and gas and show that a huge amount of gas is flowing into a central compact region,'' said team member Ana Duarte Cabral from the Laboratoire d'Astrophysique in Bordeaux, France.

The find was made possible by the high sensitivity of the Atacama Large Millimetre/submillimetre Array, located 5000 metres above sea level, in Chile's Atacama Desert.

ALMA has 66 antennas exploring the universe via radio waves emitted by galaxies, stars and other bodies not captured by telescopes, which only receive light.